1. Technical Field
The present disclosure relates to earphone jack drive circuits, and more particularly to an earphone jack drive circuit for eliminating noise generated by plugging or unplugging an earphone in or out of an electronic device.
2. Description of Related Art
Earphones are connected to an audio source via an earphone jack, and always controlled to switch between a mute mode and a normal mode by a micro-controller. The micro-controller may have a detect pin to detect if the earphone is plugged in an electronic device, and a control pin to switch between the mute mode or the normal mode. When the earphone is unplugged, the detect pin is pulled up to logic high (high voltage), the control pin is pulled down to logic low (low voltage) to enter into the mute mode. When the earphone is plugged in, the detect pin is pulled down to the logic low, the control pin is pulled up to the logic high to control to enter into the normal mode. However, during plugging in and unplugging out of the earphone, because of the unstable connection and electrical bouncing between the earphone and the earphone jack, the detect pin will be flickering between the logic low and the logic high, which causes noise such as a popping sound.